Killing of Plant Tissue by Low Temperature 



229 



when tissue above ground has begun to increase rapidly in hardiness. 

 This may be because the soil is still too cold for growth well up into 

 March, generally, and continues warm late in autumn. 



The following table gives the result of freezing young apple 

 roots (stock) kept in cold storage at a temperature of 31 to 32 F., 

 in the earth frozen up where the temperature varied from the freez- 

 ing point to 39 F., and others kept in greenhouse conditions whereby 

 they started into growth, and others kept in basement storage room 

 at a temperature varying from 4 C. to 15 C. from January 8, 1913 

 to February 16, 1913, the date of freezing. 



Table 31. Showing Relative Resistance to Low Tempera- 

 tures OF Apple Roots Kept in Dormant Condition 

 AS Compared with Those in a Grow- 

 ing Condition. 



